The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
In the standardization of evolved 3rd Generation Partnership Project (3GPP™) networks, 3GPP™ system architecture evolution (SAE) work is defining architectures where both evolved 3GPP™ wireless access and non-3GPP™ accesses are considered. Architectures for Internet protocol multimedia system (IMS) service continuity and centralized services are also defined. The technical specification (TS) 23.401 “3GPP™ General Packet Radio Service (GPRS) Enhancements for Long Term Evolution (LTE) Access” [1], the TS 23.402 “3GPP™ Architecture Enhancements for Non-3GPP™ Accesses” [2], the TS 23.237, “IP multimedia system (IMS) service continuity” [3], and TS 23.292 “IP multimedia system (IMS) centralized services” [4], which are incorporated herein by reference in their entirety, contain the current definitions for the architectures and related mechanisms.
Specifically, [1] describes an evolved 3GPP packet switched domain in multi-access networks for 3GPP™ accesses, [2] describes how network discovery and selection mechanisms work in multi-access networks for non-3GPP™ accesses, [3] describes requirements and procedures for delivery of IMS service continuity, and [4] describes requirements for delivery of consistent IMS services to a user (terminal) regardless of the attached access type.